1. Field of the Invention
This invention relates to an improved windshield wiper blade assembly and, more particularly, to an improved connection between the primary yoke and the secondary yokes.
2. Description of the Prior Art
Articulated windshield wiper blades for wiping curved and flat windshields were introduced and first disclosed in Anderson U.S. Pat. No. 2,596,063 entitled "Windshield Wiper Blade Linkage Assembly," issued May 6, 1952. The present invention primarily concerns a windshield wiper blade assembly of the articulated type shown and described in Wittwer U.S. Pat. No. 3,935,612 entitled "Windshield Wiper Blade," issued Feb. 3, 1976, and assigned to the assignee of the present invention.
The windshield wiper blade assembly shown in the Wittwer patent includes a pressure-distributing superstructure operatively connected with a resilient wiper blade. The superstructure has a primary yoke and a pair of resilient secondary yokes which, in turn, support the wiper blade. Each secondary yoke is positioned within a U-shaped channel defined by a pair of spaced apart side walls at the ends of the primary yoke. The side walls of the primary yoke have a pair of aligned openings. The midportion of the secondary yoke has a vertical open space defined by a pair of spaced apart side walls. Outwardly projecting lugs carried by the side walls of the secondary yoke align with and pivotally seat in the aligned openings in the side walls of the primary yoke to provide an articulated connection between the primary yoke and the secondary yoke. The vertical open space in the resilient secondary yoke permits the lugs to deflect inwardly as the primary yoke is urged past the lugs and outwardly into connective relationship when the lugs move into the aligned openings.
When an extreme load is placed upon a wiper blade assembly of this type, it is conceivable that pressure exerted by the primary yoke on the secondary yoke may itself cause the side walls of the secondary yoke to accidentally collapse into the open space thereby permitting the lugs to be released from the aligned openings of the primary yoke. As a result, the connection between the primary yoke and the secondary yoke is broken. Such loads might be encountered when the wiper blade is frozen to the windshield and the primary yoke is forcefully moved against the resistance of the immovable secondary yoke. In any event, this type of accidental or unintentional disconnection is undesirable during the operation of the windshield wiper mechanism.